1. Field of the Invention
The present invention relates to novel isomaltooligosaccharides, novel isomaltooligosaccharide synthase forming said oligosaccharides from dextran, and a process for producing said oligosaccharides by using said enzyme or a microorganism capable of producing said enzyme. 2. Description of the Prior Art
Conventionally, a cyclodextrin of 6-8 glucose residues bound by .alpha.-1,4 linkages is well known among cycloligosaccharides. The cyclodextrin, owing to its hydrophobicity in the center of the ring, possesses the ability (inclusion ability) to bind to a variety of hydrophobic substances. For this property, the compound has been applied and developed for stabilization and improvements in solubility etc. of various substance in a wide range of fields such as medicaments, cosmetics, foods, etc. (Handbook of Amylases and Related Enzymes, pp. 233-243 (1988), compiled by Japanese Amylase Research Society.
In recent years, cyclooligosaccharides consisting of 6-8 fructose residues in .beta.-2,1 linkage have also been found which, similar to the cyclodextrin, are expected to be applied to a wide range of fields (Carbohyd. Res., vol. 192, pp. 83-90 (1989)).
In addition to the aforementioned saccharides, a wide variety of cyclooligosaccharides, such as cyclosophoraose composed of 17-24 glucose residues in .beta.-1,2 linkage, cyclogentiooligosaccharides of 3-4 glucose residues in .beta.-1,6 linkage, cycloawaodorin with 6 rhamnose molecules cyclized, cyclomannohexaose with 6 mannose molecules cyclized, etc., have been enzymatically or chemically synthesized.
However, none of the cyclooligosaccharides of glucose residues bound by .beta.-1,6 linkages have been known so far.